The Error 1802 only appears, if a non-FRU resp. not whitelisted mPCI card is built in. Maybe the wireless card had been disabled in BIOS but still is present.

Thea reason, why this message appears now after a longer time, may be drained BIOS battery which nearly is empty now. The next boot error - message might be "set date and time" in a couple of days or weeks.

Betreff: IBM Thinkpad T40 Error 1802 help

It's also possible if you updated your computers bios, it may have had a 3rd party modified bios that does allow non-lenovo cards, but if you were to install a lenovo bios, then the error would suddenly appear.

It is very common for resellers to use modified bios, or install programs like "no-1802" in order to use non-lenovo parts. This really isn't a bad thing, on an older unit, if you wanted to upgrade to a new (faster) network card, even an official lenovo part would be rejected because it wasn't listed as an approved card when that machine was made, so the most common way to fix this is a modified bios.

Be careful if you plan to install a bios yourself, even an official lenovo bios. If the wrong bios is installed, or the computer crashes during install, or fails in any way, it could render the computer useless and only a systemboard replacement or repair could fix it, and on an older system, this would probably cost more then it would cost to replace the system.